Method for making a tire

ABSTRACT

A reinforcement ply intended for use in a tire is characterized by the fact that the reinforcement ply is formed, at least in part, of a fabric having the following properties: (a) the fabric comprises a three-dimensional body and reinforcement threads arranged in the body and held by the body; and (b) practically all the voids in the fabric are capable of being impregnated with at least one material which forms part of the structure of the tire. The invention also relates to these plies which are impregnated with at least one material which forms part of the structure of the tires. The invention further relates to tires having at least one reinforcement ply, as well as to the methods for obtaining such tires.

This application is a continuation of application Ser. No. 870,459,filed on June 4, 1986, now abandoned, which is a divisional applicationof application Ser. No. 802,865, filed Nov. 27, 1985 (now U.S. Pat. No.4,625,785, granted Dec. 2, 1986), which in turn is a divisionalapplication of application Ser. No. 579,213, filed Feb. 10, 1984 (nowU.S. Pat. No. 4,580,611, granted Apr. 8, 1986).

The present invention relates to tires. More particularly, the inventionrelates to tires having "reinforcements" intended to stiffen one or moreparts of the tires, the reinforcements being each formed of at least oneply referred to as the "reinforcement ply."

The invention concerns, in particular, tires comprising a reinforcementintended to stiffen their crown in order to permit the crown towithstand the stresses resulting from travel. This reinforcement isreferred to as the "crown reinforcement" in the body of this disclosure.

Each reinforcement ply has, in general, a practically two-dimensionalstructure, in the form, for instance, of an assembly of reinforcementcords arranged in a single thickness.

Such plies can be used as is for the production of tires by building ona drum or by pouring in a mold, as described, for instance, in theJapanese Patent Application published after examination under No.57-12,687 or in the European Patent Application published under No.5,423. In these processes, these plies are not placed directly on thesurface of the drum or mold, because in such case the tires would beexcessively fragile upon travel. Moreover, in order to impart thenecessary mechanical properties to the tires, these plies must bearranged at a given level within the thickness of the crown. These pliesare therefore arranged on a material which has been previously placed onthe surface of the drum or mold so that these plies will be protected bya substantial thickness of material in the finished tires. Thesetechniques lead to complicated and/or costly operations which result invariations in quality from one tire to the next during the course ofmanufacture.

In West German printed application No. 2,830,331 it has been proposed toprovide these plies with spurs and to then arrange these plies in a moldin such a way that the spurs rest against the surface of the core of themold. The purpose of this is to coat the plies with the poured materialon all sides. The number of such spurs is necessarily limited, and hencethe formation of only a few zones of contact of substantial crosssection each. This results in substantial interruptions of continuitywithin the tire and risks of defective bonding. Furthermore, these spurscause a break in the symmetry of revolution within the tire due to thefact that the plies assume a practically prismatic shape. All thesedrawbacks remain even if the material which forms the spurs and thepoured material are similar or identical, and these drawbacks are thesource of vibrational phenomena which are harmful both to comfort and tothe life of the tire.

French published patent application No. 2,421,969 describes a fabric ofthree-dimensional structure comprising two groups of warp threads: thewarp threads of the first group are distributed so as to form the bodyof the fabric while the warp threads of the second group are distributedso as to form at least one separating woven ply. This fabric thus makesit possible to establish an arrangement for the connecting of twomaterials of different nature without the products in question being incontact in view of the presence of the separating ply. Such a fabric isnot adapted to the production of reinforcements for tires.

The object of the invention is to eliminate these drawbacks.

Accordingly, the reinforcement ply of the invention which is intendedfor use in a tire is characterized by the fact that the reinforcementply is formed, at least in part, by a fabric having the followingproperties:

(a) the fabric has a three-dimensional body and reinforcement threadsarranged in the body and held by the body;

(b) practically all the voids in the fabric are capable of beingimpregnated with at least one material which forms part of the structureof the tire.

The invention also relates to these plies which are impregnated with atleast one material which forms part of the structure of the tires. Theinvention further relates to tires having at least one reinforcement plyas well as to the methods for obtaining such tires.

The examples which follow as well as the entirely schematic figures inthe drawing corresponding to these examples are intended to illustratethe invention and to facilitate an understanding of it, without,however, limiting its scope.

In the Drawing:

FIG. 1 shows, in radial section, a tire having a crown reinforcementcomprising two reinforcement plies according to the invention;

FIG. 2 shows, in top view, a portion of the crown reinforcement of thetire shown in FIG. 1;

FIG. 3 shows, in top view, a portion of the lower ply of the crownreinforcement shown in FIGS. 1 and 2, this ply being formed of a fabrichaving a three-dimensional body;

FIG. 4 is a section through a portion of the lower ply which is shown inFIG. 3, this section being taken along the line IV--IV of FIG. 3;

FIG. 5 shows, in radial section, a portion of a mold used for themanufacture of the tire shown in FIG. 1; and

FIG. 6 shows an undulated warp thread which forms part of the structureof the three-dimensional body shown in FIGS. 3 and 4.

FIG. 1 shows a tire 1. This tire has a crown 2, two sidewalls 3, and twobeads 4, each bead being, for instance, reinforced by a bead ring 5.

The crown 2 comprises a reinforcement 6; this crown reinforcement 6 isformed of two superposed reinforcement plies 7, 8, at times referred toas "working plies" in the tire industry, each of these reinforcementplies 7, 8 being in accordance with the invention.

FIG. 2 shows, in top view, a portion of these reinforcement plies 7, 8,the entire portion of the crown 2 present above these plies beingassumed removed. Each of the plies 7, 8 has reinforcement threads 9parallel to each other, the direction of the reinforcement threads ofone ply crossing that of the reinforcement threads of the other ply. Forclarity in the drawing, the other elements entering into the compositionof the plies 7, have not been shown in FIG. 2, these elements beingdescribed in further detail subsequently. The reinforcement threads 9 ofthe ply 7 form an acute angle α₇ with the equatorial plane of the tire1, this equatorial plane being the plane perpendicular to the axis ofrevolution of the tire 1 and passing through the middle of the crown 2.In FIGS. 1 and 2, this equatorial plane is schematically indicated bythe line zz' and in FIG. 2 the axis of revolution cf the tire 1 isindicated by the line yy'. The reinforcement threads 9 of the ply 8 forman acute angle α₈ with the equatorial plane zz'. These angles α₇,α₈ arearranged on opposite sides of the equatorial plane zz', each of theseangles being, for instance, between 15° and 30°. For clarity in thedrawing, the reinforcement threads 9 have been shown further apart ineach ply 7, 8 than they actually are.

The ply 7 is located below the ply 8, that is to say this ply 7 iscloser ro the internal cavity 10 of the tire than the ply 8 is, thecavity 10 being defined by the inner face 11 of the tire 1 and the rim12 on which the tire 1 is mounted. In other words, the radial distanceof the ply 8 is greater than the radial distance of the ply 7, theseradial distances--not shown in the drawing for purposes ofsimplification--being, by definition, measured with reference to theaxis of revolution yy' and in the equatorial plane zz'. The ply 7 iscalled the "lower ply" and the ply 8 the "upper ply." It goes withoutsaying that the width of each ply, measured along said ply, in a planecontaining the axis of revolution yy' can be equal to or greater or lessthan the width of the other ply, measured under the same conditions.Thus, in FIG. 1 the lower ply 7 has been shown wider than the upper ply8.

FIGS. 3, 4 show a portion of the lower ply 7. This ply 7 is formed of afabric 13 having two principal faces 14, 15. These faces 14, 15 areshown in the form of straight dashed lines in FIG. 4, these faces beingthen flat, that is to say the fabric 13 is shown in FIGS. 3, 4 beforeits use in the crown 2, this fabric 13 being then assumed arranged insuch a manner as to have a generally flat shape, the face 15 being theupper face of this fabric 13 and the faces 14, 15 being, for instance,parallel.

The thickness "e" of the fabric 13 is the distance between the faces 14,15.

The fabric 13 comprises a three-dimensional body 16. The reinforcementthreads 9 of this reinforcement ply 7 are part of the fabric 13 and arearranged in the body 16 and held by the body 16. This body 16 is a wovenbody formed of warp threads 17 and woof threads 18. The expression"thread" is to be understood in a very general sense, that is to sayeach of the threads 9, 17, 18 may be formed, for instance, either of asingle unit thread or of an assembly of several unit threads forming,for instance, a cable, each unit thread being possibly formed either ofa single filament or of several filaments. Each of these threads 9, 17,18 can also be formed, for instance, of an assembly of fibers or one ormore ribbons. Each warp thread 17 undulates practically within a planeP₁₇ perpendicular to the faces 14, 15, this warp thread 17 beingalternately tangent to one of these principal faces and then to theother. The woof threads 18, which are for instance linear, are arrangedbetween the warp threads 17, practically in several planes P₁₈ withinthe thickness "e" (FIG. 4), these planes being parallel to the principalfaces 14, 15. The number of these planes P₁₈ is preferably equal to atleast four. The mean orientation of the warp threads 17 and theorientation of the woof threads 18 are practically perpendicular, theplanes P₁₇ being practically perpendicular to the planes P₁₈, one ofthese planes P₁₈ being shown in dashed line in FIG. 4.

The structure of the body 16 is therefore three-dimensional, because thethreads 17, 18 which constitute it are distributed in all threedimensions. This body 16 serves as a sort of scaffolding for thereinforcement threads 9, and it is capable of retaining athree-dimensional structure even if the threads 9 are removed from thefabric 13.

The structure of the body 16 is the same as that described in FrenchPatent No. 1,526,185. The reinforcement threads 9 maintained by the body16 may constitute warp threads or woof threads of the fabric 13. It ispossible furthermore to employ woof threads 18 of such a type that theyare undulated, for instance, in order to bind the reinforcement threads9 when the latter are warp threads. The direction of the woof threads 18is then represented by their mean direction. It should be pointed outfurthermore that the threads 17 and/or 18 may possibly be replaced inpart by reinforcement threads 9. The reinforcement threads 9 arearranged in such a manner that they have no contact with at least one ofthe principal faces 14, 15.

In the example shown in FIGS. 3, 4, these reinforcement threads 9 aresubstantially linear and are arranged in a plane P₉ which is parallel tothe planes P₁₈ and located between two successive planes P₁₈. Each warpthread 17 has a mean orientation parallel to the reinforcement threads9, the reinforcement threads 9 being parallel to the planes P₁₇ andseparated from each other, FIG. 4 being a section along a plane parallelto the planes P₁₇. In the example described, the reinforcement threads 9therefore have no contact with the two principal faces 14, 15.

The structure of the upper ply 8 is similar to the structure previouslydescribed for the lower ply 7. The crown reinforcement 6 could possiblybe formed of a single ply, the reinforcement threads 9 of said ply thendescribing, for instance, circles parallel to the equatorial planewithin the tire 1. It goes without saying, furthermore, that the crownreinforcement 6 could be formed of more than two plies.

The body 16 has the sole role of holding the reinforcement threads 9.The threads 17, 18 constituting this body can therefore be made of verydifferent materials, inorganic, metallic or organic, even if theirmechanical properties and particularly their tensile strength are notvery high. For example, each of the threads 17, 18 is made with anorganic polymer in order to be of low weight. This organic polymer is,for instance, rayon, an aromatic or nonaromatic polyamide,a polyester, apolyvinyl alcohol or a polyolefin. It may be advantageous to make thethreads 17, 18 of a material which is compatible with the material withwhich they are in contact in the tire 1, or identical to said material,these threads 17, 18 being, for instance, made of polyurethanes if thetire 1 is produced by molding materials capable of reacting with eachother to give polyurethanes. It may also be advantageous to make thethreads 17, 18 of a thermoplastic material in order to facilitate thecutting out of the body 16 and/or the welding of the. ends of the body16 by thermal means.

The reinforcement threads 9 must in their turn be capable ofwithstanding the stresses to which the crown 2 is subjected. Theytherefore should have high mechanical properties, and in particular thetensile strength of these threads should be high. These reinforcementthreads 9 are made for instance of a metallic material, in particularsteel, an inorganic material, in particular glass, or an organicmaterial, for instance in order to decrease the weight and limit therisks of corrosion. This organic material may, for instance, be rayon,an aromatic or nonaromatic polyamide, a polyester or a polyvinylalcohol. It goes without saying that the threads 9, 17, 18 can be madeof identical or different materials and that each of these threads maycomprise several materials, with possibly various adjuvants, inparticular fillers.

The threads 17, 18 which constitute the body 16 preferably have a crosssection whose surface has an area smaller than the area of the surfaceof the cross section of the reinforcement threads 9 so that thecontribution made by these threads 17, 18 to the reinforcement of theply 7, 8 is as low as possible. The threads 17, 18 advantageously have across section whose surface has an area at most equal to one-quarter ofthe area of the surface of the cross section of the reinforcementthreads 9. Under these conditions, when the threads 9, 17, 18 have theshape of a circular cylinder, the diameter of the threads 17, 18 ispreferably less than the diameter of the reinforcement threads 9 andpreferably the diameter of the threads 17, 18 is at most equal toone-half the diameter of the reinforcement threads 9. When thereinforcement threads 9 of one ply 7, 8 have different cross sections,for instance different diameters, the comparison of the cross sectionsbetween the threads 17, 18 and the reinforcement threads 9 should beeffected on basis of the reinforcement threads 9 which have the smallestcross section, for instance the smallest diameter. In practice, it is,however, frequently preferably to use an identical cross section for allthe reinforcement threads 9 of the same ply 7, 8 or possibly of all thereinforcement plies 7, 8 forming part of the structure of the tire 1.With respect to the threads 17, 18 it goes without saying that theircross sections may be identical or different.

By way of example, the characteristics of the tire 1 with itsreinforcement plies 7, 8 according to the invention are as follows:

The tire 1 is of size 135-13. It is made by the casting of fluid orpasty materials capable of reacting to give a polyurethane, thisproduction taking place in accordance with a single-step process.

This process employs a mold 19 shown in part in FIG. 5. Thereinforcement 6 is placed on the core 20 of the mold 19 in such a mannerthat the lower face 14 of the ply 7 is directly in contact with theconvex face 21 of the core 20, the upper ply 8 thus resting on the lowerply 7. The two shells 22 of the mold 19 are then closed around the core20 so as to obtain a cavity 23 defined by the convex face 21 of the core20 and the concave faces 24 of the shells 22. The reinforcement 6 isthus arranged within this cavity 23 as are the bead rings 5 which havebeen previously fixed in the mold 19 by known means before closing theshells 22.

This cavity 23 has the same shape as the finished tire 1. A mixturewhich forms a polyurethane 26 in the mold 19 is then introduced, inknown manner, into the cavity 23 through the conduit 25. By definition,the voids of the fabrics 13 are the voids between the threads 9, 17, 18of these fabrics and practically all these voids 130 (FIG. 4) arecapable of being impregnated with material 26 for the plies 7, 8. Thisfeeding is effected, for instance, under vacuum, but other techniques ofproduction are possible, for instance centrifuging techniques. Theentire tire 1 is thus obtained by this casting.

For purposes of simplification, the other parts of the mold 19 as wellas the means making it possible to fasten the bead rings 5 in the mold19 have not been shown in the drawing. The lower face 14 of the ply 7therefore constitutes, in part, the inner face 11 of the tire 1 and thematerial 26 which covers the reinforcement 6 constitutes the tread 27 ofthe tire 1.

The three-dimensional body 16 of each ply 7, 8 has a thickness "e" of 2mm. The warp threads 17 and the woof threads 18 each have a cablestructure formed of two yarns of tex No. 10 twisted to 1000 S twists permeter, assembled and twisted together to 1000 Z twists per meter.

The material of these cables 17, 18 is a thermoplastic polyesterstabilized at 130° C. For each of these cables, the breaking strength is7N, the elongation at rupture is 26%, and the diameter is 0.15 mm.

This body 16 comprises 735 warp cables 17 per 100 mm and 443 woof cables18 per 100 mm. The counting of the cables 17, 18 is effected over theentire thickness "e" in a plane perpendicular to the principal faces 14,15, this plane being either oriented in the mean direction of the woofcables 18 for the counting of the warp cables 17 or oriented in the meandirection of the warp cables 17 for the counting of the woof cables 18,the distance of 100 mm being measured along the intersection of theplane in question and a principal face 14, 15. The undulation of eachwarp cable 17 is characterized by an undulation rate T=a/p, in which "a"is the amplitude of the undulation measured between two successivecrests and "p" is the wavelength of the undulation; FIG. 6 shows, by wayof example, the amplitude "a" and the wavelength "p" for a warp cable 17of the lower ply 7, two successive crests of the undulation being marked28. The warp cables 17 have a rate T of the order of 12% in the exampledescribed, but this rate T may vary within very wide limits. The shapeof this undulation may vary greatly; it may, for instance, havepractically linear segments. There are 7 planes P₁₈ of woof cables 18within the thickness "e".

Each of the reinforcement threads 9 has a cable structure formed of twoyarns of tex No. 167 twisted to 320 S twists per meter, assembled andtwisted together to 320 Z twists per meter.

The material of these reinforcement cables 9 is an aromatic polyamide.For each of these cables 9, the breaking strength is 54 daN, theelongation at rupture is 3.4% and the diameter is 0.7 mm. The plane P₉in which the reinforcement cables 9 are located in each reinforcementply 7, 8 is located, for instance, at one-quarter of the thickness "e",this plane P₉ being closer to the upper face 15 than to the lower face14. The number of these reinforcement cables 9 is 100 for a distance of100 mm measured perpendicular to the orientation of these threads 9.

The rigidity of the fabric 13 together with the body 16 and thereinforcement cables 9, on the one hand, and the rigidity of the body 16by itself are measured. Each of these rigidities is measured, on the onehand, along the mean orientation of the warp cables 17, that is to sayalong the orientation of the reinforcement cables 9, it being thencalled the "warp rigidity," and, on the other hand, along theorientation of the woof cables 18, it being then called the "woofrigidity." In each case the rigidity corresponds to the ratio F/L ε, Fbeing the force necessary to obtain a fixed relative elongation ε whichis equal in all cases to 2%, and L being the width of the fabric 13 orof the body 16 subjected to this measurement, this width being measuredalong a principal face 14, 15 perpendicular to the orientation in whichthe force F is exerted. This width is, for instance, equal to 100 mm,the ratio F/L ε being substantially independent of the value L when thenumbers of cables 9, 17, 18 corresponding to this value L are large. Therigidity values are as follows: fabric 13: warp rigidity of 466 kN·m⁻¹ ;woof rigidity of 53 kN·m⁻¹ ; body 16: warp rigidity of 8.4 kN·m⁻¹ ; woofrigidity of 44 kN·m⁻¹.

Preferably the ratio between the rigidity of the fabric 13 measuredaccording to the orientation of the reinforcement threads 9 and therigidity of the body 16 by itself measured in this same orientation isat least equal to 10 and preferably at least equal to 40, whatever thestructure of the threads 9, 17, 18, so that the reinforcement effect isdue practically only to the reinforcement threads 9. Thus, in theexample cited, the ratio of the warp rigidity of the fabric 13 to thewarp rigidity of the body 16 is equal practically to 55.

All the geometrical characteristics of the cables 9, 17, 18 which arementioned above correspond to the plies before incorporation in the tire1, these plies being then arranged in such a manner that the principalfaces 14, 15 are flat, as previously described.

Each ply 7, 8 is obtained, for instance, by cutting a ribbon out from astrip of fabric 13. The ends of this ribbon are then assembled end toend so as to produce a ring which is placed in the mold 19, the anglesα₇, α₈ being obtained by the cutting of the ribbons. Upon the end-to-endassembling of the ends of the ribbon, it is important that twosuccessive cables 9 be separated by a practically constant distance overthe entire ring obtained, including at the place of the end-to-endattachment which may be effected by welding, without this beingnecessary.

It goes without saying that the assembling of the ends of the ribbonscan be effected directly in the mold.

When the plies 7, 8 are incorporated in the tire 1, each of these plieshas the following characteristics in the vicinity of the equatorialplane:

the warp cables 17 undulate in planes P₁₇ which are practicallyperpendicular to the principal faces 14, 15, the face 15 of each plybeing, for instance, located above the face 14 of said ply, these planesforming the same angle α₇, α₈ with the equatorial plane as thereinforcement threads 9 of said ply;

the woof cables 18 are arranged practically within cylinders of axis ofrevolution yy' between the cylinders corresponding to the principalfaces 14, 15, these woof cables 18 being practically perpendicular tothe planes P₁₇ in which the warp cables 17 undulate;

the reinforcement cables 9 are arranged practically within a cylinder ofaxis of revolution yy', this cylinder being arranged between twocylinders of woof cables 18.

These arrangements, which in order to simplify the drawing have not beenshown in it, are due to the end-to-end assembling of the ends of eachribbon of the fabric 13 which has been previously described with agenerally flat shape, in FIGS. 3, 4.

The invention has the advantages described below:

(1) Each ply 7, 8 is very easy to arrange in the mold 19 since it issufficient to place it, for instance, on the core 20. Thethree-dimensional body 16 of each ply 7, 8 guarantees accuratepositioning in space of the reinforcement threads 9 within the tire 1,since it guarantees:

precise positioning of the reinforcement threads 9 with respect to eachother;

precise positioning of the reinforcement plane P₉ with respect to theface 21 of the core 20, or with respect to any other part of the moldwith which the body 16 is in contact.

(2) The precise positioning of the reinforcement threads 9 permits theproduction of tires of a very uniform quality of manufacture,practically with no risk of damage due to displacements of thesereinforcement threads during the course of manufacture.

(3) In view of the fact that, for each plv 7, 8, the body 16 which holdsthe reinforcement threads 9 has a three-dimensional structure with alarge number of threads 17, 18, this body introduces practically noheterogeneity in the tire 1. This tire then has practically perfectsymmetry of revolution, without the body 16 causing harmful vibratoryphenomena. Furthermore, there is very good bonding between thereinforcement 6 and the material with which it is in contact, so thatthis tire is characterized by satisfactory comfort and life.

(4) The plies 7, 8 are easy to produce by simple weaving, thereinforcement threads 9 being advantageously incorporated in the fabric13 upon the same weaving operation as the threads 17, 18.

(5) The plies 7, 8 can be of light weight, using, for instance, for allthe threads 9, 17, 18 organic polymers which furthermore have theadvantage of limiting the risk of corrosion.

The permeability of the fabric 13 is preferably selected in such amanner that it permits rapid migration of the mixture forming thematerial 26 into the voids 130 of this fabric 13 upon the production ofthe tire 1. For this purpose, the permeability of the fabric 13 ispreferably at least equal to 10⁻¹¹ m² ·Pa⁻¹ ·s⁻¹, this permeabilitypreferably varying from 500 to 1000·10⁻¹¹ m² ·Pa⁻¹ ·s⁻¹, these figuresbeing determined for a fluid of a viscosity of 1 Pa·s. This permeabilityis obtained with a fabric 13 whose porosity is at least equal to 50%,the porosity preferably varying from 70% to 90%. This porosity,determined by calculation, is equal to the ratio v/V, v being the voidvolume of the fabric and V the total volume of the fabric, that is tosay the sum of the void volume v and of the volume occupied by thethreads 9, 17, 18.

The permeability and porosity of the fabric 13 are measured orcalculated when the fabric is positioned so as to have a generally flatshape. These figures vary only slightly when the fabric 13 is used toproduce the tire 1, that is to say when this fabric 13 is no longerflat.

When the fabric 13 comprises one or more monofilament reinforcementthreads 9, it may be advantageous to make the fabric 13 in such a mannerthat these monofilament threads undulate slightly, for instance in theplane P₉, the undulation rate T of these threads being, for instance,less than 10%. This embodiment makes it possible to improve the fatiguestrength of these reinforcement threads 9 in the tire 1. The orientationof each undulated thread 9 is then represented by its mean orientationwhen the fabric 13 is positioned in such a manner as to have a generallyflat shape.

The invention covers the cases in which at least one ply 7, 8 isobtained directly by weaving, without it being necessary to cut thefabric 13 in order to obtain the angles α₇, α₈ in the tire 1. This istrue, for instance, in the following three embodiments when the fabric13 is arranged in such a manner as to have a generally flat shape.

(1) The fabric 13 is made in such a manner that the warp threads 17 havea mean orientation which is parallel to the sides of the ply, thereinforcement threads 9 forming within the fabric 13 woof threads whosemean orientation is parallel to that of the woof threads 18 and forms anonzero angle other than 90° with the mean orientation of the warpthreads 17.

(2) The reinforcement threads 9 form within the fabric 13 woof threadswhose mean orientation is parallel to that of the woof threads 18 of thebody 16 and perpendicular to the sides of the ply which are parallel tothe mean orientation of the warp threads 17 of the body 16.

(3) The reinforcement threads 9 form within the fabric 13 warp threadswhose mean orientation is parallel to the mean orientation of the warpthreads 17 of the body and to the sides of the ply.

In these three embodiments, the plies 7, 8 are obtained directly in theform of a fabric ribbon 13, the ends of which need merely be connectedtogether. The angle made by the reinforcement threads 9 with theequatorial plane zz' of the tire 1 is obtained directly by the positionof the reinforcement threads 9 in the ribbon 13, without cutting, thisangle being:

between 0° and 90° in the first embodiment;

equal to 90° in the second embodiment;

equal to 0° in the third embodiment.

The weaving can even be effected in such a manner that the fabric 13 ofthe reinforcement ply of the invention is obtained directly in the formof a ring, a cylinder, whether or not flattened, or any other curvedshape which may possibly correspond to the shape of the ply when it isarranged within the tire.

The invention also covers embodiments in which the fabric 13 of thereinforcement ply of the invention comprises reinforcement threads 9arranged on several levels within its thickness "e," for instance onseveral planes P₉, the direction of the threads 9 of one plane P₉crossing in particular the direction of the threads 9 of the otheradjacent plane or planes. This technique makes it possible, forinstance, to produce the entire reinforcement 6 with a single ply. Inthis embodiment, it may be advantageous to obtain the fabric 13 in themanner that the reinforcement threads 9, in at least one of these planesP₉, replace either warp threads 17 or woof threads 18 of the body 16 inorder to decrease the weight and increase the porosity and permeability.It goes without saying that these planes P₉ may possibly have differentwidths in the same ply. The above description of the use of severalplanes of reinforcement threads 9 presupposes, here again, that thefabric 13 is arranged in such a manner as to have a generally flatshape.

The invention also applies to cases in which the fabric 13 comprisesreinforcement threads 9 arranged in such a manner that they have severalorientations without these threads being arranged on planes.

This is true, for instance, when the threads 9 corresponding to eachdirection are arranged practically uniformly throughout the mass of thefabric 13. In the embodiments described above, each orientationcorresponds either to the orientation of a reinforcement thread 9, if itis linear, or to the mean orientation of a reinforcement thread 9, if itis undulated, the fabric 13 in this case also being arranged in such amanner as to have a generally flat shape. When the fabric 13 comprisesreinforcement threads 9 having several orientations, preferably for eachof these orientations, the ratio between the rigidity of the fabric 13and the rigidity of the body 16 by itself is at least equal to 10, andpreferably at least equal to 40, these rigidities being measured alongthis given orientation in a manner similar to that which was describedabove, that is to say in particular for a relative elongation of ε of2%, but in this measurement the fabric 13 comprises only reinforcementthreads 9 which have the orientation under study, the otherreinforcement threads 9 being removed. In all the aforementioned cases,it is preferably for the reinforcment threads 9 to be separated fromeach other by threads 17, 18 of the body 16 so that these reinforcementthreads 9 are without contact with each other. In this way, the abrasionphenomena of these reinforcement threads are limited.

The reinforcement threads 9 of one and the same ply may be formed ofdifferent materials, whether there be one or more orientations for thesethreads; thus, for instance, the reinforcement threads 9 correspondingto one orientation may be metallic and the reinforcement threads 9corresponding to another orientation may be made with an organicmaterial, in particular an aromatic polyamide.

The reinforcement plies of the invention can be used for tires themethod of manufacture of which is other than casting. Thus, forinstance, these plies can be used to manufacture tires by building on adrum, in particular by arranging the lower plies directly on the drum sothat they constitute at least a part of one face of the tires, thereinforcement threads being without contact with said face. In thiscase, it may be advantageous to impregnate the plies with a rubberbefore incorporating them in the tires.

The plies of the invention can be combined with conventionalreinforcement plies arranged, for instance, in the crown of the tiresover the plies of the invention.

The invention has been described above, in particular, with respect tothe production of a crown reinforcement; however, the plies of theinvention can be used to reinforce other parts of a tire, for instancethe beads. The invention is, of course, not limited to the embodimentswhich have been described above.

What is claimed is:
 1. A method for manufacturing a tire, characterizedby the following steps:(1) directly arranging at least one reinforcementply on a core of a tire casting mold having a mold cavity, thereinforcement ply being formed, at least in part, by a fabric having thefollowing properties, when the fabric is arranged in such a manner as tohave a generally flat shape with two flat principal faces: (a) thefabric comprises a three-dimensional body and reinforcement threadsarranged in the body and held by the body; (b) practically all the voidsin the fabric are capable of being impregnated with at least oneelastomer-forming material which forms part of the structure of thetire; (c) the body is capable of retaining a three-dimensional structureeven if the reinforcement threads are removed from the fabric; (d) thebody comprises warp threads, each of these warp threads undulatingpractically in a plane perpendicular to the principal faces of thefabric and being alternately tangent to one of these faces and then tothe other face; (e) the body comprises woof threads arranged between thewarp threads practically in at least four planes within the thickness ofthe fabric, these planes being parallel to the principal faces of thefabric; (f) the reinforcement threads are arranged practically in oneplane, the reinforcement threads having the same orientation, the planeof the reinforcement threads being parallel to the planes of the woofthreads; (g) the reinforcement threads are without contact with at leastone of the principal faces of the fabric; (h) the reinforcement threadsare separated from each other by the threads of the body in sudh amanner that the reinforcement threads are without contact with eachother; (i) the threads of the body have a cross-section whose surfacehas an area at most equal to one-quarter of the area of the surface ofthe cross-section of the reinforcement threads; (j) the ratio betweenthe rigidity of the fabric measured according to the orientation of thereinforcement threads and the rigidity of the body by itself measured inthis same orientation is at least equal to 10, these rigiditymeasurements being carried out for a relative elongation of 2%; (k) theporosity of the fabric is at least equal to 50%; (l) the permeability ofthe fabric is at least equal to 10⁻¹¹ m² ·Pa⁻¹ ·s⁻¹ for a fluid whoseviscosity is 1 Pa·s; (2) introducing the elastomer-forming material intothe mold cavity to form the tire and to impregnate practically all thevoids in the fabric.
 2. A method for manufacturing a tire, characterizedby the following steps:(1) directly arranging at least one reinforcementply on a building drum so that the ply constitutes at least a part ofone face of the tire, reinforcement threads in the ply being withoutcontact with said face, the reinforcement ply being formed, at least inpart, by a fabric having the following properties, when the fabric isarranged in such a manner as to have a generally flat shape with twoflat principal faces: (a) the fabric comprises a three-dimensional bodyand reinforcement threads arranged in the body and held by the body; (b)practically all the voids in the fabric are capable of being impregnatedwith at least one rubber material which forms part of the structure ofthe tire; (c) the body is capable of retaining a three-dimensionalstructure even if the reinforcement threads are removed from the fabric;(d) the body comprises warp threads, each of these warp threadsundulating practically in a plane perpendicular to the principal facesof the fabric and being alternately tangent to one of these faces andthen to the other face; (e) the body comprises woof threads arrangedbetween the warp threads practically in at least four planes within thethickness of the fabric, these planes being parallel to the principalfaces of the fabric; (f) the reinforcement threads are arrangedpractically in one plane, the reinforcement threads having the sameorientation, the plane of the reinforcement threads being parallel tothe planes of the woof threads; (g) the reinforcement threads arewithout contact with at least one of the principal faces of the fabric;(h) the reinforcement threads are separated from each other by thethreads of the body in such a manner that the reinforcement threads arewithout contact with each other; (i) the threads of the body have across-section whose surface has an area at most equal to one-quarter ofthe area of the surface of the cross-section of the reinforcementthreads; (j) the ratio between the rigidity of the fabric measuredaccording to the orientation of the reinforcement threads and therigidity of the body by itself measured in this same orientation is atleast equal to 10, these rigidity measurements being carried out for arelative elongation of 2%; (k) the porosity of the fabric is at leastequal to 50%; (l) the permeability of the fabric is at least equal to10⁻¹¹ m² ·Pa⁻¹ ·s⁻¹ for a fluid whose viscosity is 1 Pa·s; (2)impregnating practically all the voids in the fabric with the rubbermaterial before incorporating the ply in the tire.